Finding the Fourth Proportional to 978.39, 1,348.78 and 698.15

Step by Step Solution

1. Step 1: Write the proportion equation
   978.39 : 1,348.78 = 698.15 : x
2. Step 2: Convert to fraction form
   978.39/1,348.78 = 698.15/x
3. Step 3: Cross multiply
   978.39x = 1,348.78 × 698.15
4. Step 4: Simplify right side
   978.39x = 941,640.52
5. Step 5: Solve for x
   x = 941,640.52/978.39
6. Step 6: Final answer
   x = 962.44